Quick connect couplings have been widely used in the U.S. automobile industry for many years. Although applicable in numerous applications, quick connectors are most typically employed in fuel delivery systems and vapor recovery systems. The simplest and most cost effective design is the plastic housing female type quick connector releasably mated to a metal male tube end form. The opposite end of the female housing most typically defines a stem having a number of axially spaced barbs formed on the outer circumferential surface thereof and a nylon or resilient plastic tubing end form pressed thereover. Such an arrangement is described in U.S. Pat. No. 5,542,712, issued Aug. 6, 1996, entitled "Quick Connector Housing With Elongated Barb Design".
Although suitable for use in their intended applications, the aforementioned connectors are typically used to connect fluid lines that have small diameters and low pull-off requirements. One example of such a quick connector is known as an interference-type connector. This type of connector has expandable fingers mounted in a housing that create a mechanical interference on an upset portion or bead formed on the tube to be connected. The tube and upset are inserted into the connector housing past the expandable fingers. The fingers expand to allow the upset to pass and then retract behind the upset retaining the tube in the housing. The retention or pull-off force, i.e. the force required to pull the tube out of the housing is dependent upon the rigidity of the expandable fingers. Stated another way, the retention force of the interference type connector is determined in large part by the resistance to expansion of the fingers. If the fingers expand easily to allow insertion of the tube upset, the pull-off or retention force will be low. To get higher retention forces, the fingers have to be more rigid, making insertion of the upset more difficult. Additionally, fingers that are more rigid are more difficult to manually expand to remove the tube when removal is desired.
There are many applications which require very high pull-off forces, but low insertion forces. One such application is the connection of the fuel filler neck to the fuel tank of a vehicle. Pull-off forces in excess of 500 lb. are required. Correspondingly, low insertion forces of only about 20 lb. are required. Because of the need for high pull-off forces and low insertion forces, typical quick connectors are unexceptable for connecting fuel filler necks to fuel tanks. They are also unexceptable in other applications requiring high pull-off forces and low insertion forces.
Connection of the fuel filler neck to the fuel tank has historically been particularly problematic. Not only must this connection perform under high pull-off forces, it must be of robust design to sustain system integrity over an extended period of time, under severe environmental conditions and even under vehicle crash impact loads. As a result, the industry typically employs externally applied mechanical clamps interconnecting the filler tube with a flanged fitting mounted to the filler tank.
Such arrangements typically require a relatively high part count and system complexity, requiring significant labor during the manufacturing process. Furthermore, simple, less expensive traditional approaches, such as welding a flanged nipple to the outer surface of a steel tank can promote corrosion and may not meet more rigorous future structural integrity and environmental requirements.